diff --git a/src/Entity/Devices/DevicePart.php b/src/Entity/Devices/DevicePart.php
index 8e1157f2..110fabf7 100644
--- a/src/Entity/Devices/DevicePart.php
+++ b/src/Entity/Devices/DevicePart.php
@@ -78,12 +78,12 @@ class DevicePart extends AbstractDBElement
      * @ORM\ManyToOne(targetEntity="Device", inversedBy="parts")
      * @ORM\JoinColumn(name="id_device", referencedColumnName="id")
      */
-    protected Device $device;
+    protected ?Device $device = null;
 
     /**
      * @var Part
      * @ORM\ManyToOne(targetEntity="App\Entity\Parts\Part")
      * @ORM\JoinColumn(name="id_part", referencedColumnName="id")
      */
-    protected Part $part;
+    protected ?Part $part = null;
 }
diff --git a/src/Entity/Parts/MeasurementUnit.php b/src/Entity/Parts/MeasurementUnit.php
index 74fb61bc..8f8dc17a 100644
--- a/src/Entity/Parts/MeasurementUnit.php
+++ b/src/Entity/Parts/MeasurementUnit.php
@@ -66,7 +66,7 @@ class MeasurementUnit extends AbstractPartsContainingDBElement
      * @ORM\Column(type="string", name="unit", nullable=true)
      * @Assert\Length(max=10)
      */
-    protected string $unit;
+    protected ?string $unit = null;
 
     /**
      * @var bool Determines if the amount value associated with this unit should be treated as integer.
diff --git a/src/Entity/Parts/PartTraits/OrderTrait.php b/src/Entity/Parts/PartTraits/OrderTrait.php
index e0ee8744..12bcb166 100644
--- a/src/Entity/Parts/PartTraits/OrderTrait.php
+++ b/src/Entity/Parts/PartTraits/OrderTrait.php
@@ -85,7 +85,7 @@ trait OrderTrait
      *
      * @ColumnSecurity(prefix="order", type="object")
      */
-    protected Orderdetail $order_orderdetail;
+    protected ?Orderdetail $order_orderdetail = null;
 
     /**
      * Get the selected order orderdetails of this part.
diff --git a/src/Entity/PriceInformations/Currency.php b/src/Entity/PriceInformations/Currency.php
index 53bedf03..0ecfd39a 100644
--- a/src/Entity/PriceInformations/Currency.php
+++ b/src/Entity/PriceInformations/Currency.php
@@ -78,7 +78,7 @@ class Currency extends AbstractStructuralDBElement
      * @ORM\Column(type="string")
      * @Assert\Currency()
      */
-    protected string $iso_code;
+    protected string $iso_code = "";
 
     /**
      * @ORM\OneToMany(targetEntity="Currency", mappedBy="parent", cascade={"persist"})
diff --git a/src/Services/UserCacheKeyGenerator.php b/src/Services/UserCacheKeyGenerator.php
index 827479ab..66b88a7d 100644
--- a/src/Services/UserCacheKeyGenerator.php
+++ b/src/Services/UserCacheKeyGenerator.php
@@ -73,13 +73,9 @@ class UserCacheKeyGenerator
             $user = $this->security->getUser();
         }
 
-        if (!$user instanceof User){
-           throw new \RuntimeException('UserCacheKeyGenerator::generateKey() was called without a user, but no user is logged in!');
-        }
-
         //If the user is null, then treat it as anonymous user.
         //When the anonymous user is passed as user then use this path too.
-        if (null === $user || User::ID_ANONYMOUS === $user->getID()) {
+        if (null === $user || !($user instanceof User) || User::ID_ANONYMOUS === $user->getID()) {
             return 'user$_'.User::ID_ANONYMOUS;
         }